Donhou Bicycles: Experiments in Speed

Experiments in speed. Inspired by those great men of the salt flats, those men that in the 60s pushed the Land Speed Record from the 300s up towards the 600mph mark in jet-propelled cars built in their sheds. We decided to do what we do: build a bicycle, but this time, in the spirit of those pioneers of speed, build it to see how fast we could go…

The 100mph bike, speed bike or any one of the working titles that has been used for this project by the people involved. Its so far been an excersise in many things; bicycle design, back yard aerodynamics, car modification, planning, location searching, etc etc… So many things have gone into this thing being built, there really is much more to this story than the bike alone. But for now, lets talk about just that…

This “speed bike” always wanted to be a bicycle, it essentially wanted to be the same as the bikes that I build for my customers. Look past the heavy drop of those minimal bars and the huge chain ring and it is essentially a “normal” bike.

Built from opposed oval Columbus Max tubing for stiffness, reducing the chance of speed wobbles as we ride at speeds not really known about on a bicycle. The “Dog legged” drive side chain stay to give room for the 104 tooth custom machined chainring and still allow perfect chain alignment (wouldn’t want to drop a chain at 70mph plus). Custom bars to put me in the perfect position to tuck in behind the draft vehicle, nothing more needed than something to hold on to as tight as you can for the few minutes it takes to get the thing up to speed. Lots of trail built into the front end for stability at high speeds and despite the huge chainring a low bottom bracket to keep the centre of gravity as low as possible to further increase stability.

Component wise, there’s the 104 tooth chainring machined for us by Royce. The bike is fixed and the rear hub has also been supplied by Royce. The brakes have been supplied by SRAM and AVID, with the disc on the front to deal with the bulk of the slowing down; wouldn’t want to cook the carbon rims slowing from high speeds. That said there is a calliper brake on the rear, this isn’t for heavy braking and is essentially to help me slow the pedals down as there’s a lot of momentum with the large chainring and all the chain. Tokyo Fixed came through with the rest of the finishing kit.

August Wheelworks dealt with the wheel build and opted to run front and rear 24 hole, lacing the hubs to ENVE SES rims with Sapim CX-Ray spokes. They even went as far as de-anodising the E13 front hub and re polishing it to match the rear! Essentially the wheels are the only part of the bike that we needed to reduce the drag in. Drafting a vehicle means the rider and the bike itself doesn’t need to be aerodynamic. On the advise of both the rim and tyre designers we chose to run tubs as there is a risk of a clincher tyre being thrown off the rim as you go into speeds that aren’t tested on bicycle components.

In all, its a bike built purely for the purpose of going as fast as we can.